JPH05214039A - Process for producing emulsion graft copolymer - Google Patents

Abstract

PURPOSE: To obtain an emulsion graft copolymer excellent in heat stability without carrying out acid-coagulation.

CONSTITUTION: In a process for producing an emulsion graft copolymer by grafting a vinyl aromatic monomer and a comonomer onto a rubber latex in the presence of an iron (II) redox system as polymerization catalyst and coagulating the obtained graft copolymer latex with an alkali earth metal compound, the pH of the slurry after the coagulation is adjusted to a value ranging from 8 to 12 by adding an alkali metal hydroxide after or before the coagulation or coagulating the above latex with an alkali earth metal hydroxide, with the proviso that the solidified product of the slurry obtained in the above step is not washed with acidified water in a subsequent processing step.

COPYRIGHT: (C)1993,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing an emulsion graft copolymer and a composition containing the copolymer.

[0002]

BACKGROUND OF THE INVENTION Graft copolymers are used, for example, in fibers or films, for the reinforcement of natural rubber and the modification of rubber-based adhesives. One of the most important technologies for commercialization of graft copolymers is, for example, Encyclopedia
Polymer Sci. Engng., J. Wiley 1985 Vol.1, pages 3
88-426 and 1986 Vol.6, pages 1-28; Ullmanns Ency
clop. d. techn. Chemie (Encyclopedia of Industrial Chemistry of Ullmann), Verlag Chemie 1980, Vol. 19, pages 277-295 and JP-A 1-297402 and 1-21.
Emulsion polymerization as described in detail in 7005 and EP-A-76162. The preparation of the graft copolymer in emulsion involves two steps. First, an elastomer latex is produced, and in the next step a resin-forming monomer is grafted onto this elastomer latex. Typical graft initiators are persulfate or iron (II)
/ It is a redox system based on persulfate. The obtained graft copolymer latex is added with an acid such as sulfuric acid or acetic acid, or a salt such as CaCl ₂
Alternatively, it is solidified by adding MgSO ₄ . The coagulated polymer is then washed, centrifuged and finally dried at elevated temperature. Acid coagulation often results in corrosion problems in manufacturing plants as well as mold plate-out and mold corrosion during processing of finished polymers. Therefore, there is a general tendency to replace acidic coagulation with salt coagulation.

[0003]

However, graft copolymers prepared by an emulsion polymerization method using an iron (II) redox system as an initiator and then coagulated with an alkaline earth metal salt are not thermally stable. Low. Because of this, the coagulated polymer can easily be oxidized during the drying process and even start to burn. The flames, in the worst case, lead to dryer explosions and production interruptions. Other attempts have been made to solve this problem. Japanese Unexamined Patent Publication No. 1-217005 proposes to wash the dehydrated coagulated product with water having a pH of 6.1, and another washing with water having a pH of 8.2 has been proposed in Japanese Unexamined Patent Publication No. 1-297402. It is described in. Therefore, an object of the present invention is to provide a method for producing an emulsion graft copolymer having excellent thermal stability without acid coagulation and a resin composition containing the copolymer.

[0004]

According to the present invention, a vinyl aromatic monomer and a comonomer are grafted onto a rubber latex in the presence of an iron (II) redox system as a polymerization catalyst, and the resulting graft copolymer latex is treated with an alkaline earth. A method for producing an emulsion graft copolymer, which comprises coagulating with a metal compound, comprising: a) adding an alkali metal hydroxide to the resulting slurry after coagulation; and b) graft copolymer latex before coagulation. The pH of the coagulated slurry is adjusted to a value in the range of 8 to 12 by adding an alkali metal hydroxide to the above, or c) coagulating the graft copolymer latex with an alkaline earth metal hydroxide, However,
A process for the preparation of said emulsion graft copolymer is characterized in that the solidified product of the slurry obtained according to a), b) or c) is not washed with acidified water in subsequent operating steps.

Acidified water generally has a p of less than 7 by addition of an inorganic or organic acid such as hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, boric acid or nitric acid or sodium acid sulfate.
H, for example water adjusted to pH 1 to 6.9, 1 to 6.8 or 3 to 6.5.

As mentioned at the outset, the preparation of emulsion graft copolymers begins with the polymerization of the elastomer latex particles, which are the basis of the graft phase, in emulsion. These elastomer particles consist of diene rubber or acrylic rubber or ethylene / propylene / diene elastomer. Typical examples of diene rubbers are polybutadiene, polyisoprene and up to 35% by weight of comonomers such as styrene, acrylonitrile, methyl methacrylate or copolymers of butadiene with C 1 -C 6 alkyl acrylates. Acrylic rubbers are preferably crosslinked emulsion polymerized alkyl acrylates having 1 to 6 carbon atoms and copolymers thereof with up to 15% by weight of comonomers such as styrene, methylmethacrylate, butadiene and crosslinkable comonomers such as divinylbenzene. Is.

The production of rubber-based latexes by emulsion polymerization is well known. The components of a typical emulsion polymerization system are water, a monomer (eg butadiene) or a mixture of monomers (eg (butadiene and styrene), an emulsifier and an initiator system, and optionally chain transfer agents, buffers and other conventional additives. In a conventional emulsion polymerization, a hydrophobic monomer such as butadiene is emulsified in an aqueous phase with an oil-in-water emulsifier, the polymerization is usually carried out in a water-soluble initiator system, suitable emulsifiers such as anionic surfactants, For example, rosin soap or alkali metal oleate,
Stearates, or n-higher alkyl sulfonates and mixtures thereof. Polymerization can be initiated, for example, by alkali metal persulfate. Chain transfer agents, usually mercaptans such as t-dodecyl mercaptan, control the molecular weight of the elastomer particles. Suitable buffering agents are, for example, alkali metal hydroxides and pyrophosphate. The components, the manner in which they are added to the reactor, the reactor design and operating procedures all affect the characteristics of the rubber substrate latex obtained. Typical particle diameters found in elastomer latices are, for example, 0.05 to 5 μm, in particular 0.1 to 1 μm. The desired particle size can be obtained by direct growth prior to grafting or by aggregation of smaller particles.

In the well-known subsequent reaction,
Vinyl aromatic monomers such as styrene, α-methylstyrene, p-methylstyrene or vinyltoluene and comonomers such as acrylonitrile, methylmethacrylate, maleic anhydride, maleimide or N-phenylmaleimide or mixtures thereof are grafted onto the elastomer particles. Preferred examples of grafted copolymers are styrene / acrylonitrile copolymers, styrene / methylmethacrylate copolymers, styrene / maleic anhydride copolymers, styrene / maleimide copolymers and styrene / N-phenylmaleimide copolymers and It is a corresponding α-methylstyrene copolymer. A styrene / acrylonitrile copolymer is particularly preferred.

Emulsion graft copolymerization systems generally include water, elastomeric substrate latices or mixtures of substrate latices having different particle size distributions, vinyl aromatic monomers, comonomers, emulsifiers and iron (II) redox systems as polymerization catalysts and optionally chain transfer. Agents, buffers and other conventional additives. The solids content of the compound (rubber, aromatic vinyl monomers and comonomers) is usually 2 for example.
0 to 70%. The ratio of rubber is such that the rubber-aromatic vinyl monomer-comonomer charge is about 5 to 90.
%, Preferably in the range of 10 to 80%.
The weight ratio of aromatic vinyl monomer to comonomer is usually for example 1 to 8, preferably 1 to 5. Examples of typical emulsifiers, chain transfer agents and buffers have already been mentioned above. Common iron (II) redox systems include, for example, iron (II) / alkali metal persulfate, iron (II) / glucose, iron
(II) / alkali metal sulfoxylate, iron (II) / alkali metal pyrophosphate. Iron (II) [Fe (II)] is preferably present in the form of FeSO ₄ . If desired, the iron (II) redox system can be used in combination with organic peroxides such as cumene hydroperoxide, diisopropylbenzene hydroperoxide or p-methane hydroperoxide. Preferred iron (II) redox / organic peroxide system contains FeSO _4, glucose, Na-pyrophosphate and cumene hydroperoxide.
The temperature of the graft polymerization reaction is usually, for example, 20 to 100.
C., preferably 40 to 85.degree. If desired, the polymerization can be carried out under an inert gas such as nitrogen.

The coagulation of the graft copolymer latex is carried out with an alkaline earth metal compound such as MgSO ₄ or CaC.
₁₂ or a hydroxide such as Ca (OH) ₂ . Generally, for example, 0.5 to 10% alkaline earth metal compound is required, based on the weight of the dry graft polymer. The solidification temperature is, for example, 20 to 100 ° C, preferably 50 to 100 ° C.

According to the invention, the p of the solidified slurry is
H is adjusted to a value of 8 to 12, for example 8.5 to 12, 9 to 12, 9.5 to 12, 10 to 12 or 9 to 11.5. Although the pH of the slurry is largely independent of temperature, the above values preferably relate to temperatures of about 70 to 90 ° C. In a preferred embodiment of the invention, the alkali metal hydroxide is added to the graft copolymer latex before coagulation. In this case, the required amount of hydroxide can be easily determined by experimentation. At this time, the latex sample is coagulated. The amount of alkali metal hydroxide added to adjust the slurry to the desired pH can then be detected and the amount required for the latex batch calculated. In another preferred embodiment of the present invention, the pH of the slurry is alkaline earth metal hydroxide, preferably C.
It is adjusted to a value of 11 to 12 by coagulation with a (OH) ₂ .

After coagulation, the slurry is usually washed with water to neutral pH and dehydrated by centrifugation. The resin drying can be performed in one step or multiple steps. The pre-drying of the absorbed water can be carried out, for example, in a flash type dryer.
Final drying of the resin is typically done in a fluid bed or tumble dryer. The thermal stability of the resin must be considered in the drying process to prevent oxidative degradation and burning.

Conventional stabilizers, such as antioxidants, metal deactivators, phosphites, phosphonites and / or peroxide-decomposable compounds are commonly added to the latex before coagulation and are thermally stable for subsequent processing. And to provide end product stability. Usually, these known stabilizers are used at about 0.01 to about 10% by weight of the dry resin. The stabilizer is preferably incorporated in the form of an emulsion.
Examples of various conventional stabilizers are given below. 1. Examples of antioxidants: 1.1. Alkylated monophenol 2,6-di-tert-butyl-4-methylphenol, 2-
Tert-Butyl-4,6-dimethylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tertiary Butyl-4-isobutylphenol, 2,6-dicyclopentyl-4-methylphenol, 2- (α-methylcyclohexyl) -4,6-dimethylphenol, 2,
6-dioctadecyl-4-methylphenol, 2,4
6-tricyclohexylphenol, 2,6-di-tert-butyl-4-methoxymethylphenol, 2,6-dinonyl-4-methylphenol. 1.2. Alkylated hydroquinone 2,6-di-tert-butyl-4-methoxyphenol,
2,5-di-tert-butylhydroquinone, 2,5-di-
Tertiary amyl hydroquinone, 2,6-diphenyl-4-
Octadecyl oxyphenol. 1.3. Hydroxylated thiodiphenyl ether 2,2'-thiobis (6-tert-butyl-4-methylphenol), 2,2'-thiobis (4-octylphenol), 4,4'-thiobis (6-tert-butyl-3-) Methylphenol), 4,4'-thiobis (6-tert-butyl-2-methylphenol). 1.4. Alkylidene bisphenol 2,2'-methylenebis (6-tert-butyl-4-methylphenol), 2,2'-methylenebis (6-tert-butyl-4-ethylphenol), 2,2'-methylenebis [4-methyl -6- (α-Methylcyclohexyl) phenol], 2,2'-methylenebis (4-methyl-6-
Cyclohexylphenol), 2,2'-methylenebis (6-nonyl-4-methylphenol), 2,2'-methylenebis (4,6-di-tert-butylphenol),
2,2'-ethylidene bis (4,6-di-tert-butylphenol), 2,2'-ethylidene bis (6-tert-butyl-4-isobutylphenol), 2,2'-methylenebis [6- (α -Methylbenzyl) -4-nonylphenol], 2,2'-methylenebis [6- (α, α-dimethylbenzyl) -4-nonylphenol], 4,4'-
Methylenebis (2,6-di-tert-butylphenol),
4,4'-methylenebis (6-tert-butyl-2-methylphenol), 1,1-bis (5-tert-butyl-4-hydroxy-2-methylphenyl) butane, 2,6-bis (3- Tert-butyl-5-methyl-2-hydroxybenzyl) -4-methylphenol, 1,1,3-tris (5
-Tert-butyl-4-hydroxy-2-methylphenyl)
Butane, 1,1-bis (5-tert-butyl-4-hydroxy-2-methylphenyl) -3-n-dodecylmercaptobutane, ethylene glycol-bis [3,3-bis (3′-tert-butyl- 4'-hydroxyphenyl) butyrate], bis (3-tert-butyl-4-hydroxy-5)
-Methylphenyl) dicyclopentadiene, bis [2-
(3'-tert-butyl-2'-hydroxy-5'-methylbenzyl) -6-tert-butyl-4-methylphenyl] terephthalate. 1.5. Benzyl compound 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) -2,4,6-trimethylbenzene, bis (3,5-di-tert-butyl-4-hydroxy) Benzyl) sulfide, isooctyl 3,5-di-tert-butyl-4-hydroxybenzylmercaptoacetate,
Bis (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl) dithioterephthalate, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 1, 3,5-tris (4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)
Isocyanurate, dioctadecyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, calcium salt of monoethyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonate, 1,3,5-tris (3 ，
5-dicyclohexyl-4-hydroxybenzyl) isocyanurate. 1.6. Acylaminophenol 4-hydroxylauric acid-anilide, 4-hydroxystearic acid-anilide, 2,4-bis (octylmercapto) -6- (3,5-di-tert-butyl-4-hydroxyanilino) -s -Triazine, octyl N- (3,
5-di-tert-butyl-4-hydroxyphenyl) -carbamate. 1.7. β- (3,5-di-tert-butyl-4-
Esters of (hydroxyphenyl) propionic acid with the following monohydric or polyhydric alcohols Examples of alcohols: methanol, diethylene glycol,
Octadecanol, triethylene glycol, 1,6-
Hexanediol, pentaerythritol, neopentyl glycol, tris (hydroxyethyl) isocyanurate, thiodiethylene glycol, N, N'-bis (hydroxyethyl) oxalic acid diamide. 1.8. β-
Ester of (5-tert-butyl-4-hydroxy-3-methylphenyl) propionic acid with the following monohydric or polyhydric alcohols Examples of alcohols: methanol, diethylene glycol,
Octadecanol, triethylene glycol, 1,6-
Hexanediol, pentaerythritol, neopentyl glycol, tris (hydroxyethyl) isocyanurate, thiodiethylene glycol, N, N'-bis (hydroxyethyl) oxalic acid diamide. 1.9. β-
Esters of (3,5-dicyclohexyl-4-hydroxyphenyl) propionic acid with the following monohydric or polyhydric alcohols Examples of alcohols: methanol, diethylene glycol,
Octadecanol, triethylene glycol, 1,6-
Hexanediol, pentaerythritol, neopentyl glycol, tris (hydroxyethyl) isocyanurate, thiodiethylene glycol, N, N'-bis (hydroxyethyl) oxalic acid diamide. 1.10. β
-(3,5-di-tert-butyl-4-hydroxyphenyl)
Amide of propionic acid N, N′-bis (3,5-di-tert-butyl-4-hydroxyphenylpropionyl) hexamethylenediamine,
N, N'-bis (3,5-di-tert-butyl-4-hydroxyphenylpropionyl) trimethylene diamine,
N, N'-bis (3,5-di-tert-butyl-4-hydroxyphenylpropionyl) hydrazine. 2. Examples of metal deactivators: N, N'-diphenyloxalic acid diamide, N-salicyral-N'-salicyloylhydrazine, N, N'-bis (salicyloyl) hydrazine,
N, N'-bis (3,5-di-tert-butyl-4-hydroxyphenylpropionyl) hydrazine, 3-salicyloylamino-1,2,4-triazole, bis (benzylidene) oxalodihydrazine. 3. Examples of phosphites and phosphonites: triphenylphosphite, diphenylalkylphosphite, phenyldialkylphosphite, tris (nonylphenyl) phosphite, trilaurylphosphite, trioctadecylphosphite, distearylpentaerythritol diphosphite, tris ( 2,4-di-tert-butylphenyl) phosphite, diisodecylpentaerythritol diphosphite, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakis (2,2 4-di-tert-butylphenyl) 4,4'-biphenylene diphosphonite, 3,9-bis (2,4-di-
Tert-Butylphenoxy) -2,4,8,10-tetraoxa-3,9-diphosphaspiro [5.5] undecane. 4. Examples of peroxide decomposers: esters of β-thiodipropionic acid, such as lauryl, stearyl, myristyl or tridecyl esters, mercaptobenzimidazoles, zinc salts of 2-mercaptobenzimidazoles, zinc dibutyldithiocarbamate, dioctadecyldisulfide. , Pentaerythritol tetrakis (β-
Dodecyl mercapto) propionate. The simultaneous use of phenolic antioxidants and phosphites, phosphonites or peroxide decomposers is of particular importance. It is also possible to add other auxiliaries customary in plastics technology, for example pigments, fillers, reinforcing agents, lubricants, flame retardants or blowing agents.

The emulsion graft copolymers obtained according to the invention preferably have an elastomer content of 10 to 80% by weight of dry resin. Elastomer content is 30
If less than or equal to%, eg 10 to 30%, the graft copolymer may be used as such after compounding in an extruder or Banbury. However, graft copolymers with a considerable elastomer content (> 30%) are usually compounded with separately prepared polymers or copolymers to give final elastomer contents of 5 to 30%. Typical examples of such polymers or copolymers are polyvinyl chloride, polyesters, styrene / acrylonitrile copolymers, α-methylstyrene / acrylonitrile copolymers, styrene / maleic anhydride copolymers, α-methylstyrene / It is an acrylonitrile / methacrylate copolymer, a styrene / N-substituted maleimide copolymer or a mixture thereof.

Various preferred embodiments of the present invention are listed below. A) The pH of the solidified slurry was adjusted to 9 to 1 by adding an alkali metal hydroxide to the obtained slurry after solidification.
The method of the invention for adjusting to a value in the range of 2. B) The process of the invention in which the pH of the coagulated slurry is adjusted to a value in the range of 8.5 to 12 by adding alkali metal hydroxide to the graft copolymer latex before coagulation. C) KOH or NaOH in the slurry obtained after coagulation
The process of the invention wherein the graft copolymer latex is coagulated with MgSO ₄ or CaCl ₂ . D) The process according to the invention of coagulating a graft copolymer latex with MgSO ₄ or CaCl ₂ , characterized in that KOH or NaOH is added to the graft copolymer latex before coagulation. E) The process of the invention in which the graft copolymer latex is coagulated with Ca (OH) ₂ . F) The process of the invention wherein the iron (II) redox polymerization catalyst comprises persulfate, glucose, sulfoxylate or pyrophosphate, optionally together with an organic peroxide. G) The process according to the invention, wherein the solidification is carried out at a temperature of 20 to 100 ° C. H) The process according to the invention, wherein the latex is an acrylonitrile / butadiene / styrene graft copolymer latex or a methyl methacrylate / butadiene / styrene graft copolymer latex. I) The process according to the invention, wherein the antioxidant is added to the graft copolymer latex before coagulation, optionally in combination with an organic phosphite stabilizer or a peroxide decomposer. J) A compounded resin comprising an emulsion graft copolymer produced by the method of the present invention and a styrene / acrylonitrile copolymer, polyvinyl chloride or a styrene / maleic anhydride copolymer.

[0016]

EXAMPLES Several examples are given below to illustrate the invention. These examples are presented for purposes of illustration and are not meant to be limiting. Unless otherwise noted in the examples, "parts" are parts by weight and "%" are% by weight. The average particle size shown in the following examples is based on Nanosizer (Coal Tar Electric Co.) Nanosiz
er).

I) Butadiene having an average particle size of 0.07 μm /
Styrene copolymer rubber latex (latex A-1)
Preparation of deionized water 125.4 kg Sodium salt of higher fatty acid 3.4 kg Sodium pyrophosphate 0.680 kg Sodium hydroxide 0.255 kg Styrene 1.7 kg t-dodecyl mercaptan 0.051 kg Butadiene 15.3 kg 0.1275 kg of potassium persulfate is put into a 300 liter reaction tank equipped with a stirrer, a heating device, a cooling device and a raw material supply pipe. Polymerization starts at 67 ° C. One hour after the start of polymerization, styrene 6.8 kg t-dodecyl mercaptan 0.204 kg butadiene 61.2 kg is added within 5 hours at the above temperature. Within an additional 1.5 hours, the temperature is raised from 67 ° C to 80 ° C and the reaction is continued for 2.5 hours. Then, the temperature is lowered to room temperature to obtain a butadiene / styrene copolymer latex. The average particle size is 0.07 μm and the solid content is 4
It is 0.75%.

II) Butadiene / styrene copolymer rubber latex having an average particle size of 0.25 μm (latex B-
Preparation of 1) 14.7 of latex A-1 was placed in a 40 liter reaction tank equipped with a stirrer, a heating device, a cooling device and a raw material supply pipe.
kg and deionized water 2.5 kg. Then 72 g acetic anhydride and 1.4 kg deionized water were added, and 4
Mix at 0 ° C. After stirring and mixing for about 1 minute, mix 1
Leave for 0 minutes. Then, 30 g of a sodium salt of a condensate of β-naphthalenesulfonic acid and formaldehyde, 110 g of potassium hydroxide (48%) and 88 of deionized water.
Add 0 g with stirring. A butadiene / styrene copolymer rubber latex having an average particle size of 0.25 μm is obtained. The pH of this latex is 7.5 and the solids content is 29.1%.

III) Butadiene / styrene copolymer rubber latex having an average particle size of 0.65 μm (latex B-
Preparation of 2) 14.7 of latex A-1 was placed in a 40-liter reaction tank equipped with a stirrer, a heating device, a cooling device and a raw material supply pipe.
Add kg and 3.21 kg deionized water. Then 126 g acetic anhydride and 3.1 kg deionized water are added and mixed at 25 ° C. After stirring and mixing for about 1 minute, the mixture is left for 30 minutes. Then, sodium salt 90 of a condensate of β-naphthalenesulfonic acid and formaldehyde
g, potassium hydroxide 180g and deionized water 1.5k
g are added with stirring. A butadiene / styrene copolymer rubber latex having an average particle size of 0.65 μm is obtained. The pH of this latex is 7.2 and the solids content is 27.3%.

IV) Butadiene / styrene / acrylonitrile graft copolymer latex (latex C-
Preparation of 1) Latex B-1 13.7 kg Latex B-2 3.66 kg Ferrous sulfate 0.48 g Glucose 38.4 g Sodium pyrophosphate 24.0 g Deionized water 0.620 kg Stirrer, heating It is placed in a 40-liter reaction vessel equipped with a device, a cooling device and a raw material supply pipe. The temperature is increased to 60 ° C. and cumene hydroperoxide 24 g rosin soap 110 g potassium hydroxide (10%) 220 g deionized water 1.6 kg styrene 3.36 kg acrylonitrile 1.44 kg t-dodecyl mercaptan 48 g. Add continuously during 2 hours and 45 minutes. During this time, the temperature rises from 60 ° C to 70 ° C within the first 30 minutes.
After the reagent addition, the graft copolymerization is continued at 70 ° C. for another 15 minutes. The butadiene / styrene acrylonitrile graft copolymer latex obtained has a pH of 9.2 and a solids content of 39.1%. The above Preparations I to IV are described in JP-A 1-297402 and 1-2.
It is disclosed in Example 3 of 17005.

V) Preparation of Stabilizer Emulsion Emulsion-1 Stabilizer mixture (triethylene glycol-bis- [3-
100 g of (3′-tert-butyl-4′-hydroxy-5′-methylphenyl) propionate]: tris- [nonylphenyl] phosphite weight ratio 3:10) and 10 g of stearic acid are first melted at 100 ° C. , And subsequently cooled to 80 ° C. A solution of 2 g potassium hydroxide in 75 g water is heated to 80 ° C. and it is added slowly with vigorous stirring. Further, 125 g of water heated to 80 ° C. is gradually added with stirring. The emulsion obtained is stored at 50 ° C. Emulsion-2 This emulsion is triethylene glycol-bis- [3-
(3′-tert-butyl-4′-hydroxy-5′-methylphenyl) propionate]: dilaurylthiodipropionate in a weight ratio of 3: 5, except that a stabilizer mixture is used,
Prepare as for Emulsion-1.

Example 1 500 g of deionized water and 1.3 g of magnesium sulphate (5% based on dry resin) were placed in a reaction vessel equipped with a stirrer, a heating device, a cooling device and a raw material supply pipe, and up to 90 ° C. To heat. 10 stabilized with Emulsion-1 or Emulsion-2 and heated to 50-55 ° C
0 g of latex C-1 is added within 1-2 minutes with stirring at about 1000 rpm. 9 of the resulting mixture
Reheat to 0-95 ° C and bring to this temperature 10
Hold for minutes. The coagulum is separated by a suction pump while hot, washed until neutral and at 60 ° C. and 15
Dry for 15 hours at 0 mbar. The pH of the slurry is
N is added to the stabilized latex before coagulation or the slurry after coagulation.
Modified by adding aqueous aOH solution (2N). If an aqueous solution of NaOH is added to the stabilized latex before coagulation, the required amount of NaOH is determined by experiment. At this time, the latex sample is coagulated and then NaOH added to adjust the slurry to the desired pH.
Is detected and the amount required for the total latex is calculated. The effect of slurry pH on the thermal stability of the resin in differential thermal analysis (DTA) is shown in Table 1. DTA
In, the temperature dependence of a sample aerated (50 ml / min) at 180 ° C. is determined. When the polymer undergoes a decay associated with an exothermic reaction, a characteristic change in the temperature curve is observed. The time Tm required to reach the maximum of the exothermic reaction is a measure of the thermal stability of the polymer. The longer it takes to reach the maximum of the exothermic reaction, the better the thermal stability.

The coagulated samples tested were 0.3% triethyleneglyco-bis- [3- (3'-tert-butyl-4'-hydroxy-5'-methylphenyl) propionate] and 1% tris- [. Stabilized with nonylphenyl] phosphite (the amount of each stabilizer is based on dry resin).

The coagulated samples tested were 0.3% triethylene glycol-bis- [3- (3'-tert-butyl-4'-hydroxy-5'-methylphenyl) propionate] and 0.5% diethylene. Stabilized with lauryl thiodipropionate (the amount of each stabilizer was based on dry resin).

Example 2 1000 g of deionized water and 1% of calcium hydroxide (based on dry resin) were placed in a reaction vessel equipped with a stirrer, a heating device, a cooling device and a raw material supply pipe, and 90 ° C.
Heat up to. 200 g of latex C-1 stabilized with emulsion-1 and heated to 50-55 ° C
Is added within 1-2 minutes with stirring at about 1000 rpm. The resulting mixture is reheated to 90-95 ° C and maintained at this temperature for 10 minutes. The resulting slurry has a pH of 11.5. The coagulum is separated by a suction pump while hot, washed until neutral and dried at 60 ° C. and 150 mbar for 15 hours.
0.3% triethylene glycol-bis- [3- (3 '
Coagulation stabilized with tert-butyl-4'-hydroxy-5'-methylphenyl) propionate] and 1% tris- [nonylphenyl] phosphite (the amount of each stabilizer is based on dry resin) Items are ventilated (50 ml
/ Min) shows a Tm value of 78 minutes in a differential thermal analysis at 180 ° C.

Example 3 Acrylonitrile / butadiene / styrene (ABS) graft copolymer powder 50 obtained in this Example 1b
g and 50 g of styrene / acrylonitrile copolymer are blended with 1% (dry resin basis) ethylenebis [stearamide] and 1% (dry resin basis) magnesium stearate at 170 ° C./180° C. for 4 minutes on a two roll mill. Sample (40 mm x 40 mm x 2 mm)
Is compression molded from a milled sheet at 180 ° C. for 3 minutes and then heat stressed in a test oven. ASTM D 1
The Yellowness Index (YI) of the samples determined at regular time intervals according to 925 is shown in Table 3. A low YI indicates good thermal stability of the resin.

[Table 3] ^*) 0.3% triethylene glycol-bis- [3-
(3'-tert-butyl-4'-hydroxy-5'-methylphenyl) propionate] and 1% tris- [nonylphenyl] phosphite (the amount of each stabilizer is dry ABS.
Stabilized with. The data presented in Table 3 demonstrate that changing the pH of the ABS slurry also shows a significant color improvement of the formulated ABS.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location C08L 27/06 LFA 9166-4J LFE 9166-4J 51/04 LKY 7142-4J 55/02 LME 7142- 4J (72) Inventor Kurt Szczynski Switzerland 4058 Basel Lihenthi Histrace 60

Claims (13)

[Claims] 1. A method of grafting a vinyl aromatic monomer and a comonomer to a rubber latex in the presence of an iron (II) redox system as a polymerization catalyst, and coagulating the resulting graft copolymer latex with an alkaline earth metal compound. A method for producing an emulsion graft copolymer comprising: a) adding an alkali metal hydroxide to the obtained slurry after coagulation, and b) adding an alkali metal hydroxide to the graft copolymer latex before coagulation. Or c) adjusting the pH of the coagulated slurry to a value in the range of 8 to 12 by coagulating the graft copolymer latex with an alkaline earth metal hydroxide,
Process for the preparation of said emulsion graft copolymer, characterized in that the solidified product of the slurry obtained according to a), b) or c) is not washed with acidified water in subsequent operating steps. 2. The method according to claim 1, wherein the pH of the solidified slurry is adjusted to a value in the range of 9 to 12 by adding an alkali metal hydroxide to the obtained slurry after solidification. 3. The method according to claim 1, wherein the pH of the coagulated slurry is adjusted to a value in the range of 8.5 to 12 by adding an alkali metal hydroxide to the graft copolymer latex before coagulation. 4. The process according to claim 1, wherein the graft copolymer latex is coagulated with MgSO ₄ or CaCl ₂ , characterized in that KOH or NaOH is added to the slurry obtained after coagulation. Characterized by adding KOH or NaOH in 5. of procoagulant graft copolymer latex, MgSO ₄ or CaCl graft copolymer latex
The method according to claim 1, wherein the solidification is performed at ₂ . 6. The graft copolymer latex is made of Ca (O
The method according to claim 1, wherein the solidification is H) ₂ . 7. The method of claim 1 wherein the iron (II) redox polymerization catalyst comprises persulfate, glucose, sulfoxylate or pyrophosphate. 8. The method of claim 7, wherein the iron (II) redox polymerization catalyst further comprises an organic peroxide. 9. The method according to claim 1, wherein the solidification is carried out at a temperature of 20 to 100 ° C. 10. The method according to claim 1, wherein the latex is an acrylonitrile / butadiene / styrene graft copolymer latex or a methyl methacrylate / butadiene / styrene graft copolymer latex. 11. The method of claim 1 wherein the antioxidant is added to the graft copolymer latex prior to coagulation. 12. The method according to claim 11, wherein an organic phosphite stabilizer or a peroxide decomposing agent is further added to the graft copolymer latex before coagulation. 13. A compounding resin comprising the emulsion graft copolymer produced by the method of claim 1 and a styrene / acrylonitrile copolymer, polyvinyl chloride or a styrene / maleic anhydride copolymer.